The satin-effect of surfaces is achieved by a co-deposition of small particles or droplets during the electroplating process of the respective metal, e.g. nickel. The additives used for this process are adsorbed to the substrate surface causing small pits of about 0.1-0.2 μm depth and 2-20 μm in diameter. This causes a diffused light reflection on the, e.g. nickel surface. Depending on the plating process parameters, type of additives and their concentrations, many different degrees of satin-effects can be achieved. Examples for metal plating baths to produce a satin-effect are for example described in EP 1 287 184.
In order to achieve an even satin-finished nickel or nickel alloy coating an acid nickel or nickel alloy electroplating bath is proposed which contains a sulfosuccinic acid compound of the general formula (I) additional to at least one quaternary ammonium compound, wherein R1, R2=hydrogen ion, alkali ion, alkaline earth ion, ammonium ion and/or C1-C18 hydrocarbon moiety.

At present the satin-effect of metal plated surfaces is determined by optical inspections of skilled employees by visually comparing pre-plated standard samples with plated samples from the plating line. This leads to results with a low reproducibility which are strongly influenced by the human factor.
A demand exists for a method to reliably measure the satin-effect (gloss level) of metal plated surfaces which resulted in the development of a method using scattered light according to the present invention.